/Engine/Plugins/Online/OnlineSubsystem/Source/Public/Interfaces/OnlineLeaderboardInterface.h
Writes out the stats contained within the stats write object to the online subsystem's cache of stats data. Note the new data replaces the old. Stats cannot be written without a session or the write request is ignored. No more than 5 stats views can be written to at a time or the write request is ignored.
true if the call is successful, false otherwise
bool WriteLeaderboards ( const [FName](API\Runtime\Core\UObject\FName) & SessionName, const [FUniqueNetId](API\Runtime\CoreOnline\Online\FUniqueNetId) & Player, [FOnlineLeaderboardWrite](API\Plugins\OnlineSubsystem\FOnlineLeaderboardWrite) & WriteObject )